Such type of motor, which is in particular described in the patent CH 540 597, generally includes, on the one hand, a rotor provided with a permanent magnet of the bipolar type, and shaped to furnish a motor couple to a mechanism to be driven and, on the other hand, a stator on which are arranged three energization windings respectively driven by an appropriate control circuit.
The stator is provided with a peripheral stator portion having a form essentially circular which forms around the rotor a low reluctance magnetic circuit. Three branches extend from such peripheral stator portion towards the axis of rotation of the rotor so as to form, through their free end, three polar expansions.
Such branches are normally oriented towards the rotational axis of the rotor and they present longitudinal geometric axes intersecting substantially at the rotational axis of the rotor, and displaced from one another by 120.degree.. Each of the driving windings which may be energized by one of the phases of energization via the control circuit, is mounted on one of the branches and generates a magnetic flux. In driving the control circuit, generally one associates several magnetic fluxes with the permanent field of the magnet which, by creation of a mutual couple, cause the rotor to turn.
Such type of motor exhibits numerous advantages.
It offers a good yield, but also it is particularly adapted, as much to function in continuous rotation as in a bidirectional mode.
Nevertheless, with such a motor, because of its particular structure such as has been defined hereinabove, one encounters problems of high manufacturing costs which evidently limit its interest, above all when it must be employed as transducer or again as driver in a relatively high number of copies for each product, as is generally the case in applications such as robotics, automobiles, aeronautics, aerospace or again biomedical engineering. In effect, the motor previously described has essentially as vocation the development of relatively high power, for example for driving vehicles, with the result that it has not been conceived so as to be capable of being made in very large series at low cost, but simply in order to be able to offer adequate output characteristics.
This invention has as purpose to overcome such difficulties by furnishing an electromagnetic motor capable of operating in a polyphase energization mode, preferably three phase, of simple construction, that is to say, capable of being made in very large series at a very low cost price.